Conventionally, there have been many types of image processing apparatus for inspecting, recognizing, determining, or analyzing objects with use of images. Generally, most of them perform the image processing by using a computer which processes an image as a digitized image. Among the conventional types, there is also an apparatus which displays an image in two-tone such as black and white, or red and blue, by converting density of pixels into a binary system, as 0 and 1. The present invention relates to an image processor having object recognition ability which deals with the images which are processed by binary system, i.e., binary images. In this case, a pixel is defined as one of the points which compose a screen, i.e., an element, and an image is defined as a pixel having density value. In the binary image system, an image displayed as 1 or in black is called an active image. On the other hand, an image which is displayed as 0 or in white is called a non-active image.
Conventionally, a labeling system has been utilized so that the image processing apparatus is able to recognize an object which appears to be a mass of object to human eyes. In the conventional labeling system, it is arranged that the active image objects, which are adjacent each other and considered to be a mass, are labeled as "A, B, C . . .". The objects labeled in the same letter, for example as "A", are recognized to be in the same group.
However, the conventional labeling system is associated with the following disadvantage. Even though it is appeared to be a mass to human eyes, if there is one missing pixel in the object, the apparatus recognizes the object as the two separate objects. For example, as in FIG. 4, if there is a gap 55 between each pixel in the right and left sides of a golf club as a result of an interruption by noise or the like, the image processing apparatus recognizes the golf club as the two separate objects, a club head 51 and shaft 50. The image processing apparatus may recognize the left object as a hammer, the right object as a bar. Thus, it has been very difficult for the conventional image processing apparatus to recognize an object with gaps as a whole, even though it is appeared to be the golf club to human eyes, i.e., one continuous object.